Technical Field
The present invention relates to a device for the splinting and/or holding open of a cavity, an organ duct and/or a vessel in the human or animal body with at least one compressible and self-expanding stent which has at least one expanded phase.
Prior Art
Syndromes based on the at least partial closure of cavities, organ ducts and/or vessels are increasing sharply due to the effects of civilisation. An important area of such syndromes relates to the air passages. For example obstructive sleep apnea is a life-threatening illness resulting from the closure of the rear air passages due to muscle relaxation during sleep. Through repeated and sometimes very frequent interruption of breathing during sleep, the patient is not adequately supplied with oxygen, in extreme cases leading to death. Civilisation-related factors such as e.g. severe obesity or excessive alcohol consumption seriously increase the risk of illness. Snoring is a gentler outcome of the effect than sleep apnea, but results from the same organic cause. Whereas people are aware of snoring, the serious risks to health especially of heavy snoring and of sleep apnea are often not registered, since the patient is not aware of the organic deficiency symptoms.
FIG. 1 shows free airways through which normal breathing takes place. The relaxation of the tongue and of the surrounding muscles in the pharyngeal cavity which occurs during sleep leads, due to the inflowing air, to vibrations of the soft palate and the soft parts of the throat, resulting in the noise of snoring. Strong relaxation of the throat tissue and the falling back of the root of the tongue may lead to complete closure of the air passages (FIG. 2). After a certain time (approx. 60-90 seconds) the brain generates a waking reaction. The transition from snoring to apnea is fleeting. The interruption of breathing may last up to 1.5 minutes and be repeated 200-400 times during the night, which does not allow the patient any deep sleep. The consequences are restless sleep, tiredness during the day, high blood pressure, lack of drive, etc. If the illness is not treated, then the body is unable to regenerate adequately in sleep, leading to a lower expectation of life. Increased fluctuations of pressure within the thorax may in certain circumstances have adverse effects on the cardiovascular system. Consequences of snoring are high blood pressure and a drop in the oxygen content of the blood. It is nowadays assumed that in particular during sleep apnea, but also during snoring, significant organic consequent illnesses may occur.
The Health Technology Assessment Report, volume 25 “The Sleep Apnea Syndrome” by Perleth et al., Asgard Verlag St. Augustin 2003, establishes on the basis of epidemiological studies a prevalence of sleep apnea among around 2-4% of the population of Germany, i.e. roughly 2 to 3 million affected persons. In diagnostic tests conducted in sleep laboratories, accordingly, around half of all patients turned out to be affected by apnea and urgently in need of treatment. Other sources assume a proportion of only 5% for diagnosed illness treated by therapy. According to Prof. Dr. Frank Michael Baer of the University Clinic, Cologne, a third of the male population of Germany are regular snorers. Snoring requires treatment for 4% of men and 2% of women aged between 30 and 60 years. At the same time, the incidence of snoring rises sharply with age. Thus, while only about 10% of the population snore at the age of 20, this rises to around 50% at the age of 50. In short, sleep apnea is an illness of socially relevant character with increasing prevalence and importance, in which only a small portion of those affected are known and receiving treatment. There is therefore also a need for new, simple, but effective options for therapy.
The current standard therapy for sleep apnea is the active supply to the patient of respiratory air under overpressure by means of an n-CPAP breathing apparatus (nasal continuous positive airway pressure). Through the night-time wearing of a breathing mask, through which a continuous positive airway pressure is generated, the air passages are held sufficiently open. The principle of operation is illustrated in FIG. 3. Significant drawbacks to this standard therapy, which is to date the sole treatment option with medical effectiveness, are the discomforts to the patient, created above all by the wearing of an airtight oxygen mask for the whole night, fixed via an adequately strong headband and connected via the supply tube to the breathing apparatus; also through drying out of the mucous membranes and the need for moistening of the respiratory air, plus the operating noise of the breathing apparatus. In addition to the severely restricted freedom of movement during sleep, there is the risk of air escaping due to leaks between the breathing mask and the skin of the face, so that the overpressure is accidentally reduced and may no longer be sufficient. Moreover, acceptance of the nightly wearing of a breathing mask is very limited in time for many patients, even though life-long therapy is required. The HTA report referred to above reported that the acceptance of CPAP treatment, in particular long-term, is relatively low. Less than half of patients to whom CPAP was recommended carried out the treatment long-term (i.e. for more than one month). It was notable that, despite proof of significant therapeutic effectiveness only for the CPAP mask, there was a clear but subjective preference by patients for an intraoral splint, probably due to the lower subjective stress of this therapy. The intraoral splint is claimed to provide at least partial improvement of symptoms by ensuring breathing through the mouth. A further drawback of the CPAP mask is the need to take the breathing apparatus with one when travelling. There is also the time and effort required for cleaning and maintenance.
On account of these severe stresses and restrictions for the patient, apnea patients suffer a high degree of mental trauma and have great interest in alternative and subjectively more tolerable therapy options. The prevailing view is that as yet no efficient alternative treatment option has been developed which may be used routinely, and is also practicable and cost-effective.
A large number of proposals have been made for the physical prevention of snoring and apnea, but none have become established on the market. Described in DE 195 01 363 is a device for insertion through the mouth, characterised by a tube which may be introduced into and fixed in the pharynx. It is meant to prevent the collapse of the soft parts of the pharynx. A drawback cited by the inventor is the need to overcome nausea. Experience shows that the route described here, via the mouth, is impracticable, and does not lead to adequate reduction of symptoms. A similar device to support the soft palate parts in the nose and throat area, but which is intended for introduction through the nose, is proposed in DE 100 28 013. The effect is just as limited as the instrument described above. Alternatively, in WO 98/23233 it is proposed to introduce a double tube through the nose to maintain the air supply passage, but this is just as ineffective as the two instruments described above. DE 102 40 725 describes a probe against apnea and snoring, which is expandable at the end by means of a drawing element. It is not described how in practice the expansion by means of the drawing element takes place or how the expanded probe is stabilised in the air passage.